04-02-2025, 10:33 AM
Regarding the oscillator circuit which is comprised of the 6A7's cathode, control grid, and screen grid. These elements are configured as a triode, so more or less the cathode should be @ 0v, control grid a small amount - voltage like -3 or -4v, and the screen grid a high + potential like +80v. If the control grid is reading a + voltage the oscillator is not running. The voltage must be measured w/ a high input impedance meter so the meter won't load the circuit.
#s 13 and 14 have to be in the circuit to resonate the SW section of the osc coil. If I counted my 0s right it's a .002250mmfd or pf. If you had a .0022 ceramic disc cap you could chuck that in so #8 can tune 6-18mc.
#17 and 18 are the grid leak resistors for the osc. 17 is for the BC/POL band and 18 for the SW band. They too need to be in the circuit. As for the POL band I need to do a little research cause it looks like voodoo...
https://philcoradio.com/library/download...20217B.pdf
#s 13 and 14 have to be in the circuit to resonate the SW section of the osc coil. If I counted my 0s right it's a .002250mmfd or pf. If you had a .0022 ceramic disc cap you could chuck that in so #8 can tune 6-18mc.
#17 and 18 are the grid leak resistors for the osc. 17 is for the BC/POL band and 18 for the SW band. They too need to be in the circuit. As for the POL band I need to do a little research cause it looks like voodoo...
https://philcoradio.com/library/download...20217B.pdf
When my pals were reading comic books
I was down in the basement in my dad's
workshop. Perusing his Sam's Photofoacts
Vol 1-50 admiring the old set and trying to
figure out what all those squiggly meant.
Circa 1966
Now I think I've got it!
Terry
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